Patent EA-001348-B1 (EA)
Title: Travelling spark ignition system and ignitor therefor
Inventor: SUCKEWER SZYMON
IPC: F02P9/00
Filed: 1997-05-29
Abstract: 1. A traveling spark ignition (TSI) system for a combustion engine, comprising an ignitor including: substantially parallel and spaced apart electrodes, including at least first and second electrodes forming a discharge gap between them, the first electrode being an outer electrode and the second electrode being an inner electrode and both electrodes having substantially circular configurations in cross-section, an outer radius of the inner electrode and an inner radius of the outer elctrode being referred to as the radii of the electrodes, the length of a said electrode being relatively short with respect to the dimension of the gap and the dimension of the gap being relatively large with respect to said length, such that the ratio of the sum of the radii of said electrode to the length of the said electrode is larger than or equal to about four, while the ratio of the difference of these two radii to the length of the said electrode is larger than about one-third, dielectric material surrounding a substantial portion of said electrodes and the space between said electrodes, an uninsulated end portion of each of said electrodes being free of said dielect ric material and in oppositional relationship to one another; means for mounting said ignitor with said free ends of said first and second electrodes installed in a combustion cylinder of said engine; and electrical means for providing a potential difference between said electrodes fo r initially providing thereto a sufficiently high first voltage for creating a channel formed of plasma between said electrodes, and a second voltage of lower potential than said first voltage, for sustaining a current through the plasma in said channel between said electrodes, whereby an electric field from the potential difference between said electrodes and a magnetic field arising from said current interact in a manner creating a force upon said plasma for causing it to move away from its region of origin, thereby increasing the volume of said plasma, said electrical means provides forming said first and said second voltages so that total energy provided to said ignitor for ignition is less than about 1% of the energy in the combustible mixture being in the combustion cylinder. 2. The TSI system of claim 1 wherein said electric means includes: a first voltage source for providing said first voltage having a relatively high amplitude but low magnitude of current; and a second voltage source for providing said second voltage of substantially lower amplitude than the first voltage but with higher magnitude of current relative to that from said first voltage source. 3. The TSI system of claim 1, further including: said ignitor further including a third electrode located between said first and second electrodes; and said first voltage being applied between said second and third electrodes, and s aid second voltage being applied between said first electrode and said second electrode. 4. The TSI system of claim 1, wherein said first and second electrodes are parallel cylinders. 5. The TSI system of claim 1, wherein said first and second electrodes are of the same length. 6. The TSI system of claim 1, wherein the axial length of the uninsulated portion of the first and second electrodes is smaller than or equal to about 3 mm and the radial separation of the electrodes is from about 1 mm to about 3 mm. 7. The TSI system of claim 1, wherein said parallel first and second electrodes are parallel to a longitudinal axis of said ignitor. 8. The TSI system of claim 1, wherein uninsulated surfaces of the said parallel first and second electrodes that face each other are of the form of annular sections of disks oriented in a plane perpendicular to a longitudinal axis of said ignitor. 9. The TSI system of claim 8, wherein the radial width of said uninsulated part of annular disks is smaller or equal to about 3 mm and the separation of the electrodes is about 1 mm to about 3 mm. 10. A traveling spark ignition (TSI) system for a combustion engine using gaseous combustible mixture, comprising: at least two parallel and spaced apart electrodes adapted for forming a discharge gap between them. the length of at least one of the electrodes being relatively short with respect to the dimension of the gap and the dimension of the gap being relatively large with respect to said length, such that the radius of the largest cylinder which can fit between said electrodes is greater than the length of at least one of said electrodes; dielectric material surrounding a substantial portion of said electrodes and the space between said electrodes; an uninsulated end portion of each of said electrodes being free of said dielectric material and in oppositional relationship to one another, said uninsulated end portions being designated the lengths of said electrodes, respectively; means for mounting said ignitor with said free ends of said electrodes in a combustion cylinder of an engine; and electrical means for providing two voltages between said electrodes. the first voltage applied being sufficiently high for creating a channel formed of plasma between said electrodes, and the second voltage applied of lower amplitude than said first voltage, for sustaining a current through the plasma in said channel between said electrodes,  whereby an electric field caused by the voltage between said electrodes and a magnetic field arising from said current interact in a manner creating a force upon said plasma for causing it to move away from its region of origin between the electrodes, thereby substantially increasing the volume swept by said plasma, said electrical means provides applying two voltages so that total energy provided to said ignitor for one ignition is less than about 300 mJ. 11. A plasma ignitor for an internal combustion engine, comprising: at least first and second electrodes; means for maintaining said electrodes in predetermined, spaced-apart relationship to establish a discharge gap between them; the electrodes being dimensioned and configured and their spacing being arranged so that a length of at least one of the electrodes is relatively short with respect to the size of the gap and the size of the electrode gap is relatively large with respect to said length, such that when a sufficiently high voltage is applied across the electrodes while the ignitor is installed in a combustion cylinder of a combustion engine, in the midst of a gaseous mixture of air fuel, a plasma is formed from the fuel-air mixture between the electrodes and said plasma moves outwardly from between the electrodes into an expanding volume in the cylinder, under a Lorentz force, said high voltage is applied so that the total energy provided to said ignitor for one ignition is less than about 1% from the energy of the gaseous mixture, and means for mounting the ignitor with active portions of the first and second elec trodes installed in a combustion cylinder of a combustion engine. 12. The ignitor of claim 11 wherein the electrodes have substantially circular surfaces facing each other in parallel, spaced apart relationship with radii and separation suitable for formation of the plasma and the plasma moving radially outwardly when the high voltage is applied. 13. The ignitor of claim 11 wherein the electrodes are spaced apart and parallel longitudinal electrodes, and the plasma moves longitudinally outwardly from between the electrodes when the high voltage is applied. 14. The ignitor of claim 13, further including a dielectric material surrounding a substantial portion of the electrodes and the space between them; an uninsulated end portion of each of the electrodes is free of the dielectric material and in oppositional relationship to one another, the uninsulated end portions being designated the lengths of the electrodes; and the radius of the largest cylinder which theoretically can fit between the electrodes is greater than the length of the electrodes divided by six. 15. The ignitor of any of claims 12-14, wherein the ratio of the sum of the ra dii of the electrodes to the length of the electrodes is larger than or equal to about four , while the ratio of the difference of these two radii to the length of the electrodes is larger than about one-third. 16. The ignitor of claim 13 wherein a dielectric material surrounds a substantial portion of the electrodes and the space between them; and an uninsulated end of portion of each of the electrodes is free of said dielectric material and in oppositional relationship to one another. 17. The ignitor of claim 11 wherein a dielectric material surrounds a substantial portion of the electrodes and the space between them with an uninsulated end portion of each of the electrodes being free of the dielectric material and, in oppositional relationship to one another, such that as said voltage is applied, the plasma is formed first on or in the vicinity of the dielectric material. 18. The ignitor of claim 11 wherein including a third electrode located between said first and second electrodes; and said first voltage being applied between said second and third electrodes, and said second voltage of substantially lower amplitude than the first voltage being applied between said first electrode and said second electrode. 19. The ignitor of claim 1 wherein the total energy provided to said ignitor for one ignition is less than about 300 mJ. 20. The ignitor of claim 11 wherein the total energy provided to said ignitor for one ignition is less than about 300 mJ. 21. The ignitor of claim 1 wherein the ratio air/fuel in the combustible mixture is less stoichiometric mixture. 22. The ignitor of claim 11 wherein the ratio air/fuel in the combustible mixture is less stoichiometric mixture.